Where is the ground wire on 87 535i fuel injector

Hi check your instrument cluster and see if a red dot is flashing rapidly when u crank engine over. Could be related to transponder chip in your key not reading. Security engages and cuts off fuel injectors to the motor. If u have a spare key try that. Hope the info helps

Those sensors wouldn't affect power to the injectors.

You need a voltmeter, it's an electrical problem, so you need a digital volt/ohm meter (DVOM), or also called a multi-meter, and digital because many car circuits that are computer related operate at very low voltages or power demands, from milliamps to thousands of volts, like the ignition delivers to the spark plugs. So you buy a cheap multi-meter, then you also need a wiring diagram for your car to see how the fuel injector circuit works. but start there where you plugged in the new injector harness.

You are looking for power to the injectors, with key on. The injector harness has 8 wires; each injector has a power wire and a ground wire, so 4 of the wires in the harness should have power. At least on most American cars, the injector works by having the ecm control the ground for the injector . The power is constant. It is only when the ecm momentarily internally grounds the injector circuit that the injector fires. On your VW, the injector power wires and ground wires both go to the ecm.

When you ground the hot you are basically connecting it to the neg of the battery and completing the circuit, so its telling you, you have an open ground circuit at the injector. Its strange that all of them would have the same issue at the same time, so I would be checking the ground circuit on each injector from the injector back to the main harness connection. Attach your meter in Ohms to each one in turn, then move the harness around pull it, twist it, etc the meter reading should not change, if it does that circuit is bad. Then look at the main connector carefully, the pins get very greasy and the wires become brittle and the insulation gets hard and breaks off. Then do the same with the plug going back to the computer. Somewhere the bad ground will show up. If all is OK, most likely the computer's internal switching of the ground is bad.

It could be a fault in the wiring for #1 injector, or a defective spark plug in #1.

All four injectors have a hot wire to them with key on, the same black with red stripe wire is spliced to all four. Check if #1 has this hot wire with key on. The injector ground wire for #1 and #3 is a white wire with red stripe. These two ground wires splice together before the ground wire enters the computer. So the computer pulses #1 and #3 injectors simultaneously. (Injectors 2 and 4 have a similar set up, with a white wire being their ground.) If you have a hot wire to #1 injector, but no pulse on it, but #3 injector is pulsing (putting fuel into the cylinder), then the ground wire for #1 may be broke before it connects with the #3 injector ground. The wires and the splice are probably buried inside the engine wiring harness, so one could check for continuity on the ground side for 1 and 3. With key off, use an ohmmeter and check resistance between the grounds for #1 injector connector and #3-check on the harness side of the injector connectors-it should show low resistance-low ohms value. If very high resistance is shown, trace the ground wire from #1 injector.

look for a bad ground, you can try running a new ground from the battery to the body, i had an 89 corsica that would not fire until i ran the new ground wire.

fuel pressure regulator is the only thing left that can cause no start due to fuel problem

Try looking at fuel pressure regulator.

Check the fuel injector ground circuit from the ECM

i would check for any LOOSE OR MISSING GROUND WIRES that were originally bolted to either the bellhousing/starter bolts or if the wiring harness that runs over the tranny and connects to tranny switches has been cut/damaged. you would be suprised how many problems can occur because of bad/ missing grounds!!

Hi and welcome to FixYa,

Test the wires leading to the injectors. One would be +12 when IGN switch is turned ON/RUN, the other should be pulsating when engine is cranked/running. If this other wire is not pulsating and/or reading 0 volts, then the computer would need looking into. To perform the test, a test light or DVM/VOM would be needed. If this is the case, then initially check for any loose connection including the ground wire/strap in the computer harness/area.

Good luck and thank you for using FixYa.